Drive system for the transmission of power from a power source to a plurality of output trains

ABSTRACT

A drive system for the transmission of power from a drive source to a plurality of output trains includes a transfer gear connected upstream of the output trains, and an arrangement for ensuring that the output trains are not overloaded with torque. The arrangement includes a safety clutch with a basic clutch body for the frictionally engaged connection of two machine parts, and at least one thin-walled sleeve which forms a wall of an annular chamber upon which pressure medium can act. The arrangement further includes at least one feed line which extends through the clutch body to the annular chamber and can be closed off in an air and fluid-tight manner by use of closure elements. The arrangement finally includes a pressure-relief mechanism. The safety clutch is arranged upstream of the transfer gear. The pressure-relief mechanism is coupled to an arrangement for detecting the torque at the output trains and/or a magnitude which is proportional to the torque and is associated with each output train, and/or an influencing quantity in the area surrounding the machine. The clutch includes a device for activating the pressure-relief mechanism when the torque and/or a magnitude proportional to the torque and/or an influencing quantity is/are exceeded.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a drive system designed to transferpower from a power source onto a plurality of drivetrains.

2. Description of the Related Art

Many industrial drive system concepts are based on the distribution andtransfer of power, originating from a power source onto several powerconsumers, which are positioned downstream of the power consumer. Asignificant area of application of such a drive system concept are rollmills. The power developed by a motor is transferred via drivetrainsonto several working rolls. For that purpose, a transfer gearbox isconnected ahead of the drivetrains. The transfer gearbox includes in itssimplest form only several spur gears, which are positioned in a mannerthat allows the transfer of power onto the downstream positioneduniversal drivetrains in accordance to the ratio of the spur gears. Thedrivetrain can further include apparatuses for torque and speedamplification. Disturbances on the driven equipment cause aninterruption of the torque transfer from the driving to the drivensystem, resulting in an unacceptable increase in torque. In roll mills,these types of disturbances manifest themselves as jams during therolling process. The cause of such jams is primarily a result of alamination of the rolling stock, the use of cold rolling stock, or afracture of the roll. The reason for such an unacceptable increase intorque is the continued propulsion of the masses in spite of thedisturbances on the driven side of the drivetrain. This manifests itselfin a deformation of the drivetrain, which can lead to torsionalfractures in extreme cases. In order to avoid such failures, as well asprevent the unacceptable torque increase, special and quickly separablesafety couplings are available for the transfer of torque between twomechanical components on the same axis. An exemplification of such acoupling, including an overload safety device, designed to preventexcessive torque spikes, is published in the German paperDE-OS-29-23-902. The coupling includes at least one thin-walled sleeve,forming a wall of a ring-shaped chamber extending in axial direction.The ring-shaped chamber can be pressurized with a medium in order toelastically deform the sleeve in radial direction causing it to jamagainst the surface of an element onto which the coupling is mounted.Adjacent to the ring-shaped chamber are drillings, which are a part of asafety or coupling relief device. As a result of the relative motionbetween the surfaces and the actions of the relief device, thepressurized medium residing in the ring-shaped chamber can escapethrough the drillings, thus lowering the pressure inside the chamber.

To transfer a certain torque level, a certain surface pressure isrequired. For that purpose, oil is pumped into the chamber, which isneeded to deform the respective machine components relative to oneanother. In this way, the coupling is adjusted to the desired torquecapacity. If, during an overload condition, this torque is exceeded, thecoupling slips. The maximum torque level that can be transmitted reducesbecause the effective, static friction coefficient transitions into thesliding friction coefficient. There is a relative motion incircumferential direction between the individual elements of the twomachine components, which are jammed relative to one another. A sheardisk mounted on one machine component shears off a shear valve, openingthe connection to the ring-shaped chamber of the coupling. Aftershearing off the shearing valve (or valves), the pressurized oil canfreely expand and the torque to be transmitted reduces to zero within afew milliseconds. Such couplings are placed in a sensible manner inareas of possible disturbances.

For an application in a roll mill, the safety coupling must bepositioned near the rolls. This, however, is not always feasible, whichis why such a safety coupling must be mounted either in every universaldrivetrain or immediately ahead of every universal drivetrain. Thisdisadvantage of such an arrangement of safety couplings in a drivetrain,especially in an application such as a roll mill, is the high cost,since every universal drivetrain or branch of a power take-off isassigned a safety coupling. Furthermore, there is a direct relationshipbetween the size of the safety coupling and the torque to betransmitted. Higher torque levels require a larger diameter safetycoupling, which is met by limitations as a result of the placement ofthe universal drivetrains or the individual power take-offs, as well astheir center-line distances to one another.

SUMMARY OF THE INVENTION

The present invention provides a drive system of the type mentioned inthe introduction, which avoids the disadvantages. An overload safetydevice for preventing a torque overload condition is cost-effective,easy to manufacture, as well as fast-responding. The overload safetydevice for preventing a torque overload condition is effective at torquelevels that are only minimally above the maximum allowable torque. Themagnitude of the maximum allowable torque to be transmitted is adjustedso that, if this torque is exceeded, the torque transmission can bequickly disrupted. Furthermore, the overload safety device designed toprevent a torque overload condition offers a rapid response time, i.e.,a short period of time between the occurrence of an unacceptable hightorque level and the interruption of the torque transmission.

The overload safety device is a cost-effective solution with respect tothe construction and function, including only a small number ofrelatively simple components. The entire arrangement is characterized bylow manufacturing and assembly costs, as well as by minimum effortrequired to reset the coupling after a triggering event, i.e., after aninterruption of a torque transmission.

By placing the safety coupling--including a coupling body tofrictionally engage two machine components and a reliefmechanism--upstream from the transfer gear box, only one coupling isrequired to protect against a torque overload condition. The reliefmechanism cannot be designed as described in German documentDE-OS-29-23-902, but the relief mechanism must be designed to operate ata faster response time. This response time should correspond to afraction of the natural frequency of the drive system in order to avoiddeformations in the drivetrain. This is accomplished by use of anexternal relief method, i.e., by directly or indirectly controlledopening of the supply drillings. To disrupt the torque transfer atrelatively low torque spikes on the individual power take-offs,especially the universal drivetrains, an appropriate relief mechanism isprovided, which is connected to a torque sensing/acquisition deviceassigned to every universal drivetrain, and/or a device to capture avalue proportional to the expected torque value, and/or a device tocapture a disturbance value originating in the vicinity of the machineand affecting the operation of the machine.

The safety coupling is a remote operated coupling, which is triggered inresponse to a predetermined value for the current torque value, and/or acharacteristic value proportional to the torque, and/or the occurrenceof a disturbance value. In terms of the triggering method, there areseveral possibilities that should be considered: sensing of the torqueof each power take-off, especially of each universal drivetrain, and/orsensing of a value proportional to the torque on the individual powertake-offs (for example: the roll forces, speed differences observed in aroll mill), and/or sensing of parameters of the materials to beprocessed which are indirectly proportional to the torque value (in rollmills--temperature and thickness of materials) and/or the capture of thedisturbance value impacting the manufacturing process of the machine ina retroactive fashion (for example: vibration in the foundation).

The determined values can be compared to a not-to-be-exceeded commandvalue in order to generate a signal to control the relief mechanism byuse of a control device. A mechanical device is also feasible.

As far as the possibilities to trigger the relief mechanism, there are aplurality of possible variations. The relief mechanism includes, forexample, a shear device to separate the shear valve, which keeps thepressurized medium from escaping from the ring-shaped chamber of thecoupling. The shear device is mounted in a freely rotatable mannerrelative to the coupling body, including at least one thin-walled sleeveforming a wall of the pressurized, ring-shaped chamber. The mounting isdesigned so that the shear device is rotating together with thedrivetrain nearly without difference in rotational speed in relation tothe shear valves. The coupling between the relief mechanism and thespeed-sensing/acquisition device of each universal drivetrain works onthe basis that when the maximum allowable torque and/or a characteristicvalue, proportional to the maximum allowable torque is exceeded, or atthe occurrence of a disturbance value, the shear device is reduced inspeed. Because of the resulting rotational speed difference, the shearvalves are sheared off in response to the relative circumferentialmotion difference between the shear device and the shear valves, causinga relief of the pressurized medium in the ring-shaped chamber. The forceor torque transfer is therefore disrupted.

Another possibility is to include at least one machine element in therelief mechanism, including an explosive substance which, in the eventof an overload condition, is triggered to explode, allowing the supplydrilling to open. The explosive substances are either solid, liquid, orviscid substances or substance mixtures which, after ignition by sparks,flames, or impact, etc., rapidly release large amounts of compressiblegases, causing destructive effects in its immediate surroundings. Forthe triggering and relief of the coupling and the storage of theexplosive substance, there are at least two possibilities. Thetriggering can occur directly, i.e., the explosive substance isintegrated directly in the sealing valves and ignited there. Thetriggering by the machine element carrying the explosive substance canoccur indirectly, i.e., the relief mechanism includes a shear device.The explosive substance is applied to "connectors" and is activated atthe site of the shear device.

The basic principle, according to this invention, is the placement of acost effective safety coupling--designed to prevent a torque overloadcondition--and the design of the appropriate relief mechanism, which isa part of the safety coupling, into a drivetrain whereby the powergenerated by a power source is distributed onto multiple powerconsumers.

The shear device, designed in the form of a ring with oblong openings,partially encompasses the shear valves, which usually protrude onlyminimally above the outer periphery of the coupling body. Shear devices,especially, the shear disk, and the main body of the coupling shouldboth be mounted on the same machine component. The braking or thestopping of the shear device can be accomplished in different ways. Theuse of a disc brake, drum brake, ratchet mechanism, or the applicationof systems with pre-loaded springs which can be electro-magneticallyreleased are feasible. From a cost perspective, the simplest solution isthe use of a disk or drum brake. The shear device or the shear disk is,in this case, extended in radial direction and includes--along thisdirection--a working surface for the brake disks. Preferably, theextension in radial direction is chosen to be as large as possible inorder to provide the largest possible working surfaces for the brakedisks which, in turn, reduces the braking pressures of the disks.

If a ratchet mechanism is used to slow down the shear device or sheardisk, the ring has a gear tooth pattern found on the side facing awayfrom the shear valves (in radial direction) as well as on a surface inradial direction. This gear tooth pattern forms the notches for theengagement of a ratchet or a locking pin. The locking pin or ratchet is,in normal operation, held in a fixed position in relation to the machineframe. When the maximum allowable torque is exceeded, a magnet attachedto one of the universal drivetrains is activated in order to unlock theratchet or locking pin and, subsequently, to move the ratchet or lockingpin into the notches for engagement.

For the response time, that is, the period of time between the sensingof the unacceptably high torque and the sheering off of the sheervalves, the number of notches or the speed of the movement of theratchet or locking bolt into the notches is the key factor. Throughappropriate design measures, this response time can be optimized. Forsensing the torque, or for determining a value proportional to thetorque on the universal drivetrain or on the rolls, or for determiningthe disturbance value, different systems of sensing or capturing thesevalues can be used. The torque sensing and/or the determination of thevalue proportional to the torque and/or the disturbance value can beaccomplished mechanically, electronically, or optically. Mechanicalsensing/acquisition devices are based on the strain gage principle or ona mechanical torque measurement device. It is also feasible to usecombinations of the various methods for sensing torque.

The coupling of the device, used to measure the torque and/or the valueproportional to the torque and/or the disturbance value, to the reliefmechanism is best accomplished electronically. Mechanical coupling isfeasible; however, it requires precise manufacturing tolerances sincethe distance between the sensing location and the sheering device isusually very large. The connection between the sensing/acquisitiondevice and the relief mechanism can be accomplished, for example, by useof an electronic control device whose inputs include "torque exceeded"and whose outputs include a signal to slow down the sheer device or toignite the explosive substance.

Through the placement of the safety coupling ahead of the transfergearbox, one single safety coupling is sufficient in such a drivetrainto protect against a torque overload condition. The coupling body, whosepurpose is to establish a frictional engagement between two machinecomponents, is positioned, corresponding to the torque to betransmitted, ahead of the transfer gearbox. The shear device isactivated externally, i.e., not directly through deformation in thedrivetrain when exceeding the maximum allowable torque and/or the valueproportional to the torque. Thereby, a very cost-effective solution toprevent a torque overload condition in a drivetrain can be realized. Thedesign of such a relief mechanism is done in a manner to achieve theshortest possible response times, i.e. the shortest possible time spanbetween the occurrence of torque spikes and the interruption of thetorque flow ahead of the transfer gearbox. The spacing between thedrivetrains no longer limits the torque capacity of the safety coupling.

Preferably, the oblong openings of the shear device, especially theshear disks, which encompass the shear valves, are made to differentwidths. This means that during braking or stopping of the shear disk,the shearing events of the individual shear valves occur sequentially.This has the unique advantage that the shearing forces required to shearoff the shear valves are relatively low. The shearing of the shearingvalve occurs in a sequential manner, i.e., the shearing of one valve isfollowed by the shearing of the next valve, which contributes to asubstantial improvement in the running smoothness of the drive system.If all valves are sheared off at the same time, relatively high forcesare required, which leads to undesirable, high vibration levels in thedrive system. The number of shear valves provided on a coupling body andthe number of oblong openings in the shear device should be the same. Itis, however, feasible to design a shear disk with a certain number ofoblong openings in such a way so that it can be adapted to differentcoupling bodies, resulting in the opportunity to take advantage of theconcept of modular construction.

Preferably, all coupling elements, that is, all elements that serve todisrupt the flow of the torque, are made with small masses in order toquickly overcome the inertia of the masses during activation of therelief mechanism.

An embodiment of a safety coupling includes a machine element (i.e, aseparator bolt) containing the explosive substance serving to activatethe shear device by ignition of the substance. In doing so, conventionalshear devices are applied--a shear disk for example, which is placed ina fixed position relative to the coupling body and, when triggered, thering can be moved in axial or radial direction relative to the couplingbody. An additional device to accelerate this relative motion isfeasible by the use of pre-loaded springs, for example. There should beat least two separator bolts mounted equally-spaced around thecircumference of the driveshaft. The shear device itself can be mountedin a torsionally rigid manner onto the driveshaft, although it should bedesigned to be moveable in axial direction. One possibility of such anarrangement includes the use of a splined shaft connection between thedriveshaft and the shear device. The shear device can also be mounted ina freely rotating manner on the driveshaft. A torsionally rigidconnection is not necessarily required, although it appears to be a goodsolution when applied in combination with a shear disk, since the diskwith the respective oblong openings can be designed to accommodate thesealing valves, which are frequently designed in the form of valves.

The separator bolt is coupled with an ignition device, which isactivated in response to a signal from the sensing/acquisition device.The sensing/acquisition device should be a control device including atleast one input for actual values and one output. The two inputs areeach connected to a sensing/acquisition device which determines thecurrent torque value and/or the value which is directly or indirectlyproportional to the torque, and/or a disturbance value. The actual valueis compared with either a fixed or a calibratable maximum allowablevalue stored in the control device. If a deviation occurs, a signal isissued at the output of the control device, initiating the triggering ofthe relief mechanism, or in this case, the ignition of the separatorbolt. Since the data transfer, the data comparison, and the triggeringof the relief mechanism occurs at the speed of light, such a safetycoupling is especially useful for rapid triggering during a torqueoverload condition or during any other disturbances. The reliefmechanism can be triggered immediately upon recognition of a torquespike or even prior to that event. Mechanical sensing/acquisitiondevices always have some delays in this regard.

A further possibility is to locate the shear device by use of pre-loadedsprings or separator bolts (which also need to be ignited) and upon atriggering event, (i.e., the result of an overload condition) anacceleration of the shear device toward the sealing valves takes place.The shear device can be designed so that it interacts with the sealingvalves in radial as well as axial direction. The addition of thepre-tension accelerates the relief action.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a schematic, sectional side view of a safety coupling in adrive system as applied to a roll mill;

FIG. 2a is a partial, schematic, sectional side view of the reliefmechanism of FIG. 1, shown with a disk brake acting upon a shear disk;

FIG. 2b is a top view of the relief mechanism of FIG. 2a;

FIG. 3a is a schematic, fragmentary, sectional view of a ratchetmechanism of the present invention;

FIG. 3b is a schematic, sectional view of the ratchet mechanism of FIG.3a;

FIG. 4 is a fragmentary, front view of the shear disk of FIG. 2b alongline I--I.

FIG. 5 is a schematic, side, sectional view of another embodiment of arelief mechanism, according to this invention, with an element such as aseparator bolt, containing the explosive substance; and

FIG. 6 is a partial, schematic, sectional side view of yet anotherembodiment of a relief mechanism, according to this invention, with apre-loaded shear device.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate one preferred embodiment of the invention, in one form, andsuch exemplifications are not to be construed as limiting the scope ofthe invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and particularly to FIG. 1, there is showna design of a drive system frequently used in a roll mill application,with at least two universal drivetrains and an integrated device toprotect against a torque overload condition. A working roll 1 and aworking roll 2 are each driven by a respective universal drivetrain 3and 4. The power generated by the power source 5 (i.e., an electricmotor) is transferred to the universal drivetrains 3 and 4 by use ofappropriate speed/torque converters. The connection of motor 5 to thegear reduction unit 6 is accomplished by use of a torsionally rigidcoupling 7, which can be designed as a denture clutch. Downstream of thegear reduction unit 6 is a transfer gearbox 8. Transfer gearbox 8 servesto distribute the power to the individual universal drivetrains 3 and 4.Between the gear reduction unit 6 and the transfer gearbox 8, residesthe safety coupling 9. Safety coupling 9 serves to--in addition totransmitting torque from the gear reduction unit 6 to the transfergearbox 8--to protect against a torque overload condition. Safetycoupling 9 includes a coupling body 24 and a relief device 31. Couplingbody 24 includes at a least thin-walled sleeve 12, forming a wall 13 ofa ring-shaped chamber 14 extending in axial direction. Ring-shapedchamber 14 can be pressurized with a medium in order to elasticallydeform the sleeve 12 in radial direction. The realization of thenon-positive connection between the gear reduction unit 6 and thetransfer gearbox 8 by use of safety coupling 9 can be accomplished inseveral ways. For example, flange 15 can be connected to output shaft 10of gear reduction unit 6 in a torsionally rigid manner. Flange 15 isconnected to input shaft 11 of transfer gearbox 8 by use of couplingbody 24 in a non-positive manner. Coupling body 24 of safety coupling 9divides the drivetrain into two parts--a first part I, which isconnected to the power source or motor 5, and a second part, which isconnected to the power take-off--in this case the working rolls 1 and 2.Transfer gearbox 8 is, in the presented exemplification, designed toinclude a set of spur gears. These include spur gears 16 and 17. Spurgear 16 is mounted torsionally rigid onto transmission input shaft 11 oftransfer gearbox 8. Transmission input shaft 11 is the same shaft as theoutput shaft 19 of the transfer gearbox 8. Spur gear 17 is mountedtorsionally rigid onto a second transmission output shaft 20 of thetransfer gearbox 8. Output shafts 19 and 20 of the transfer gearbox 8are connected torsionally rigid to universal drivetrains 3 and 4.

The relief mechanism 31 can be designed in different ways, asexemplified in FIGS. 2 and 3. Relief mechanism 31 serves to provide apressure relief in the ring-shaped chamber 14. The activation of therelief mechanism 31 occurs through coupling 45 with thesensing/acquisition devices, in this case the torque sensing/acquisitiondevice 46 and 47 which are assigned to the universal drivetrains 3 and4. Coupling 45 can be a control device. The torque sensing/acquisitiondevices 46 and 47 can be of various types. To acquire the torque,mechanically-based torque sensing/acquisition devices can be utilized.These can be designed as published in the brochures by the corporation,"Ringspan". These work on the basic principle that a small torsionaldeformation is converted into an axial movement by use of a leversystem. This axial motion is then converted into a voltage signalproportional to the torque by use of an inductive difference generator.These torque-proportional voltage signals can subsequently function asinput signals to a control/regulator unit, which processes these signalsinto an output signal for the activation of the shear device.

The safety coupling, designed to protect against a torque overloadcondition, is placed--in the case of a roll mill--between transfergearbox 8 and gear reduction unit 6. This assures that safety coupling 9is positioned as closely as possible to the origin of possibledisturbances. It is also possible, although not shown here in detail, tointegrate the gear reduction unit 6 and the transfer gear box 8 into oneunit. Denture clutch 7 would, in this case, no longer be necessary andwould be replaced by safety coupling 9. In such a case, the torque flowis disrupted directly between the power source, in this case, motor 5,and the transfer gearbox 8.

FIGS. 2a and 2b depict, in accordance to this invention, across-sectional view of relief mechanism (ref. FIG. 1) for a safetycoupling using disk brakes to slow down the shear disk. The labelingused in this illustration is the same as used in the previousillustration. Safety coupling 9a connects the fist part I of drivesystem with the second part II, through the jamming of flange 15 of thefirst part of the drive system against bushing 26 and bushing 27, aswell as against the transmission input shaft 11 of the transfer gearbox8 of the second part II of the drive system.

To this end, the ring-shaped chamber 14 is pressurized with a medium.The ring-shaped chamber 14 utilizes supply drillings 28, which reside onthe outside 29 of the coupling body 24 and extend in the radialdirection to the ring-shaped chamber 14. The supply drillings 28 aresealed by sealing valves, also referred to as shear valves 50. Shearvalves 50 protrude only minimally above the outer periphery 29 ofcoupling body 24. Coupling body 24 is mounted rotatable on bushing 27,which, in turn, is connected torsionally rigid to transmission shaft 11of transfer gearbox 8. Also mounted on bushing 27 is the shear disk 30of relief mechanism 31.

Shear disk 30 includes a radial extension in form of a ring 32. Diskbrake device 33 is also mounted in a freely rotating manner relative toshear disk 30. All elements of the safety coupling 9a are tied to theaxis A, which means that none of these parts are mounted externally onthe framework, preventing the transfer of vibration onto the framework.Disk brake device 33 includes a central housing 34 with two disks 35 and36, which can be pressed against surfaces 37 and 38 of ring 32. Theactivation of the disk brake device can be electronically controlled.Shear disk 30 comprises oblong openings 39, which partially encompassshear valves 50, as shown in FIG. 2b, view x, as referenced in FIG. 2a.The oblong openings 39 should be open to the side.

When the disk brake device 33 is activated, disks 35 and 36 are pressedagainst surfaces 37 and 38 of ring 32 and the rotational speed of theshear disk 30 reduces until it comes to a standstill. This creates arelative motion between the oblong openings 39 and the shear valves 50,causing valves 50 to be sheared off. This, in turn, opens the supplydrillings 28, relieving the pressure inside chamber 14. The non-positiveconnection between the first and second part of the drive train issuspended and the torque flow is interrupted.

FIGS. 3a and 3b illustrate a device designed to slow down or stop theshear disk 30 in accordance to FIG. 1. The same components are labeledusing the same reference numbers as used in the previous Figures. Sheardisk 30 includes, in this embodiment also, oblong openings 39 that areopen to the side, which partially encompass shear valves 50. Shear disk30 is, in this version also, extended in radial direction. Shear disk 30includes on the circumference 40 notches 41, positioned in radial oraxial direction. Notches 41 can be designed in form of a sawtoothpattern. Engaged with notches 41 is at least one locking element, whichcan be in the form of a ratchet 43 or a locking bolt 44. Bothpossibilities are shown in FIG. 3a. The activation of locking bolt 44occurs perpendicular to axis A of the transmission input shaft 11. Whenusing ratchet 43 to slow down or lock shear disk 30, the locking actionoccurs by pivoting the ratchet 43 around a fixed pivot point P1. Forthis purpose, ratchet 43 is positioned radially off to the side as faras possible. Ratchet 43 is held in its position by use of pre-loadedsprings 46. The activation of the ratchet 43, that is, the pivotingaround P1, is accomplished by magnet 47. Correspondingly, the activationof locking bolt 44 can also be accomplished by magnet 47.

FIG. 4 illustrates a preferred embodiment of a shear disk, which can,for example, be applied to the relief mechanisms 31, which are depictedin FIGS. 2 and 3. The shear disk and coupling body are shown here inview I--I (ref. 2b). The coupling body 24 includes a plurality of supplydrillings 28 (shown here by dash-point-dash lines), leading to thering-shaped chamber 14. These drillings 28 are sealed by shear valves50, or in this case, valves 50a, 50b, 50c. Shear disk 30a, whichencompasses part of coupling body 24, includes oblong openings 39, whichshould be open to the side. The oblong openings 39, in this case, 39athrough 39c, are made to different sizes, so that the distances S₁through S₃ between the edges of the oblong openings 39 and the interfacesurfaces of the shear valves 50a through 50c--in direction ofrotation--become increasingly larger. This has the result that valves 50are sheared off in a sequential manner at relatively low forcerequirements.

FIG. 5 illustrates, in accordance with the intent of this invention, arelief mechanism 31 for a safety coupling 9 using a shear disk 30 whichis activated by use of a separator bolt (also shown in FIG. 1). Thelabeling used in this illustration is the same as used in the previousillustration. Safety coupling 9 connects the first part I of the drivesystem to the second part II, through the jamming of flange 15 of thefirst part I of the drive system against bushing 26, as well as againstthe transmission input shaft 11 of the transfer gearbox 8 of the secondpart II of the drive system.

To this end, the ring-shaped chamber 14 is pressurized with a medium.The ring-shaped chamber 14 utilizes supply drillings 28, which reside onthe outside 29 of the coupling body 24 and extend in the radialdirection to the ring-shaped chamber 14. The supply drillings 28 aresealed by sealing valves, also referred to as shear valves 50. Shearvalves 50 protrude only minimally above the outer periphery 29 ofcoupling body 24. Mounted on bushing 26 is an element 27 carrying sheardisk 30 of relief mechanism 31. The shear disk 30 is connected toelement 27 in a torsionally rigid fashion, for example, by use of asplined shaft connection 55. Shear disk 30 is moveable in relation tobushing 27 in axial direction, parallel to the centerline of the driveshaft. Acting on shear disk 30 is at least one separator bolt in form ofan explosive bolt 51. If several explosive bolts 51 are used, then theseshould be placed on the shear disk 30 on the same diameter andequally-spaced. The explosive bolts 51 are connected to an ignitiondevice, which is linked to the output of a control device--not shownhere--although it could be the same control device 45, as shown inFIG. 1. In response to the input signal, an output signal is initiatedto trigger the ignition process, corresponding to the torque anddisturbance values, which have been established.

FIG. 6 illustrates an additional embodiment that includes a shear disk30 that is pre-loaded by spring 53. During normal operation, the sheardisk is located in its position relative to the sealing valves 50 by useof separator bolts 51. In the event of an overload condition, theseparator bolts 51 are fired, and the shear disk is accelerated in axialdirection to shear off the valve heads of the sealing valves 50 of thesafety coupling 9. "Dynamit Nobel" (a corporation) publishes theseparator bolts 51 and the elements holding the explosive substances invarious forms in brochures.

In terms of the placement of the separator bolts 51 in relation to theshear device, (preferable a shear disk 30) there are many other designalternatives. However, they all have one thing in common: uponrecognition of a torque spike, a firing of the explosive substanceoccurs, generating an immediate force acting on the valve, which, inturn, causes the sealing valves to vent, triggering an interruption ofthe torque transmission by hydraulically jamming sleeves and bushings.More design variations are accorded to the expert's discretion, which iswhy these additional design variations are not further elaborated here.

While this invention has been described as having a preferred design,the present invention can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A drive system for transferring power in adirection of power transfer from a power source, said drive systemcomprising:a plurality of power take-off drivetrains; a transfer gearboxdisposed upstream from said drivetrains relative to the direction ofpower transfer; a control device configured for processing an acquiredvalue of at least one of a torque on said power take-off drivetrains, avalue proportional to the torque which is assigned to each said powertake-off drivetrain, and a disturbance value, said disturbance valuequantifying a disturbance originating nearby; and a protection deviceconfigured for protecting against a torque overload condition in atleast one of said drivetrains, said protection device including a singlesafety coupling disposed upstream from said transfer gearbox relative tothe direction of power transfer, said safety coupling having:a reliefmechanism connected to said control device; an activating deviceconfigured for activating said relief mechanism upon at least one of thetorque, the value proportional to the torque, and the disturbance valuebeing exceeded; and a coupling body configured for achieving anon-positive connection between two machine components, said couplingbody being configured to limit thereto deformations needed to achievethe non-positive connection and to thereby avoid deformations to saidtwo machine components, said coupling body including at least onethin-walled sleeve partially defining a ring-shaped pressurizablechamber, said coupling body also including at least one supply drillingextending through said coupling body to said ring-shaped chamber, saidat least one supply drilling being configured for being sealed withsealing valves in a fluid-tight manner.
 2. The drive system of claim 1,wherein said power take-off drivetrains include a plurality ofsensing/acquisition devices, said safety coupling including a controldevice having at least one input linked to at least one of an ambientenvironment and said sensing/acquisition devices, said control devicehaving at least one output configured for sending an activation signalto said relief mechanism.
 3. The drive system of claim 1, wherein saidpower take-off drivetrains include a plurality of sensing/acquisitiondevices, said safety coupling including a converter coupled to saidsensing/acquisition devices, said converter being configured forconverting signals from said sensing/acquisition devices into anactivation signal for triggering said relief mechanism.
 4. The drivesystem of claim 1, wherein the value proportional to the torquecomprises an operating parameter of said power take-off drivetrains. 5.The drive system of claim 1, wherein the value proportional to thetorque comprises an operating parameter of a material to be processed.6. The drive system of claim 1, wherein the disturbance value comprisesa value for current vibrations in a foundation of said drive system. 7.The drive system of claim 1, wherein said relief mechanism includes ashear device configured for acting upon said sealing valves, said sheardevice being freely rotatable relative to said coupling body.
 8. Thedrive system of claim 7, wherein said shear device comprises a sheardisk including a plurality of openings, said openings at least partiallyencompassing said sealing valves.
 9. The drive system of claim 8,wherein said openings have different widths.
 10. The drive system ofclaim 8, wherein said shear device includes a brake device.
 11. Thedrive system of claim 10, wherein said brake device comprises a diskbrake device, said shear disk including two ring-shaped extensionshaving two working surfaces configured for engaging said disk brakedevice.
 12. The drive system of claim 7, wherein said shear deviceincludes:a shear disk including a ring-shaped radial extension having aperipheral edge with a plurality of notches; and a brake device havingan engaging device configured for engaging said notches upon activationof said relief mechanism.
 13. The drive system of claim 12, furthercomprising a pre-loaded spring element configured for holding saidengaging device in a fixed position, said engaging device including amagnet configured for generating a force counteracting said pre-loadedspring element upon activation of said relief mechanism.
 14. The drivesystem of claim 12, wherein said coupling body includes a center line,said engaging device including a locking bolt configured for slidinginto said notches in a direction substantially parallel to said centerline of said coupling body.
 15. The drive system of claim 12, whereinsaid engaging device comprises a ratchet, said ratchet being pivotableabout a fixed pivot point.
 16. The drive system of claim 1, wherein saidrelief mechanism includes:a shear device configured for acting upon saidsealing valves; and at least one machine element containing an explosivesubstance and configured for acting directly upon said sealing valves,each said machine element being connected to said control device;wherein said safety coupling includes an ignition device configured forigniting said explosive substance upon one of the torque and the valueproportional to the torque being exceeded.
 17. The drive system of claim16, wherein said shear device comprises a shear disk.
 18. The drivesystem of claim 17, wherein said shear disk is pre-loaded.
 19. The drivesystem of claim 16, further comprising a drive shaft torsionally rigidlyconnected to said shear device, said shear device being movable in anaxial direction.
 20. The drive system of claim 1, further comprising aplurality of sensing/acquisition devices, said control device comprisingan electronic coupling device interconnecting said relief mechanism andsaid sensing/acquisition devices.